docs: def update_function_configuration(self, vpc_config):
          """Update existing Lambda function configuration.
  
          Args:
              vpc_config (dict): Dictionary of SubnetIds and SecurityGroupsIds for using
                                 a VPC in lambda
          """
          LOG.info('Updating configuration for lambda function: %s', self.app_name)
  
          try:
              self.lambda_client.update_function_configuration(
                  Environment=self.lambda_environment,
                  FunctionName=self.app_name,
                  Runtime=self.runtime,
                  Role=self.role_arn,
                  Handler=self.handler,
                  Description=self.description,
                  Timeout=int(self.timeout),
                  MemorySize=int(self.memory),
                  VpcConfig=vpc_config)
  
              if self.concurrency_limit:
                  self.lambda_client.put_function_concurrency(
                      FunctionName=self.app_name,
                      ReservedConcurrentExecutions=self.concurrency_limit
                  )
              else:
                  self.lambda_client.delete_function_concurrency(FunctionName=self.app_name)
  
          except boto3.exceptions.botocore.exceptions.ClientError as error:
              if 'CreateNetworkInterface' in error.response['Error']['Message']:
                  message = '{0} is missing "ec2:CreateNetworkInterface"'.format(self.role_arn)
                  LOG.debug(message)
                  raise SystemExit(message)
  
              raise
          LOG.info('Updating Lambda function tags')
  
          lambda_arn = get_lambda_arn(self.app_name, self.env, self.region)
          self.lambda_client.tag_resource(Resource=lambda_arn, Tags={'app_group': self.group, 'app_name': self.app_name})
  
          LOG.info("Successfully updated Lambda configuration.")